Kathy Hilton was "very concerned" about her sister Kyle Richards when Mauricio Umansky was spotted on a date with someone else

She told 'Entertainment Tonight': "Eventually it was gonna happen, and I think it's very difficult to see. I was concerned about her. But I spent the whole day with her that day."

The former 'Real Housewives of Beverly Hills' star - who is mother to Paris, 43, Nicky, 40, Barron, 34, and Conrad, 30 through her marriage to businessman Richard Hilton - recently revealed her sibling had been having a mix of "good and bad" days since the split.

She said: "You know, there's good days for Kyle and then there's tough days. And I am there talking to her every day, several times, and I wanna be there for her. It's very scary after almost 28 years. She's been married her whole life. And the four children. It doesn't matter what age. It's heartbreaking."

Mauricio recently told his daughters he did "everything possible" to save his marriage and that he had an "amazing" relationship with Kyle, who also has Farrah, 35, with first husband Guraish Aldjufrie.

Speaking in a clip from the season two premiere of 'Buying Beverly Hills', he told them: "I had an amazing 26 years with your mom, and I wanted to do everything possible to just save it. Your mom came and she talked to me and said, 'I think I need space.' "She said to me, 'Listen, the rules are: you go out, you date, you do whatever it is you want to do. I'm not going to be asking you what you're doing, I don't want you to be asking me what I'm doing. We are separated...'"